Workers have been removing old concrete foundation slabs and treating contaminated soil on the 16-acre Pfister Chemical site, which runs along the east side of the Overpeck, south of Route 46. The property was contaminated with volatile organic compounds, especially xylene and chlorobenzene, as well as some PCBs.

The site had been dormant for 14 years. Pfister Chemical had made several attempts to sell the property to a developer, but it was stymied by the fact that any developer would first have to deal with a potentially expensive cleanup. Matrix New World Engineering of Florham Park was hired to handle the cleanup, which is expected to be completed by the end of this year.

"After 70 years, people forget what’s in the ground," said Patrick Hunnewell, director of operations at Blue World Remediation, also of Florham Park, which is also working on the cleanup. "We had some historical information about what was here, but we found more concrete. In one spot we found three layers of foundations."

Contaminated concrete was shipped off to a landfill in Pennsylvania. The rest was crushed and set aside for use as fill later on, said Sullivan. The soil above the water table has been scraped into piles, and is treated in place with hydrogen peroxide, which oxidizes the contaminants and converts them to non-toxic compounds. "We spray it on the piles and mix it in," said Edward Sullivan, director of the licensed site remediation program at Matrix New World Engineering. "It’s low tech but effective."

Formed in 1990, Matrix is a leading woman-owned full-service engineering and environmental services firm. Matrix is working on a wide range of infrastructure, building and environmental projects for public and private-sector clients throughout the United States. The Florham Park, NJ-based company has offices in Eatontown, NJ, as well as New York City, Louisiana, Texas, and Arizona.